I use aquacore for server management i just installed it onto my factions servers and i did /staffmode and got this:
---- Minecraft Network Protocol Error Report ----
// +'${`%&NO CARRIER

Time: 2025-01-28 19:39:52
Description: Packet handling error

java.lang.IllegalStateException: Player is either on another team or not on any team. Cannot remove from team 'e§4'.
at fcg.b(SourceFile:308)
at ggb.a(SourceFile:2154)
at aff.a(SourceFile:132)
at aff.a(SourceFile:18)
at yz.lambda$checkThreadAndEnqueue$0(PacketUtils.java:44)
at net.optifine.util.PacketRunnable.run(PacketRunnable.java:28)
at bra.d(BlockableEventLoop.java:210)
at bre.d(SourceFile:23)
at bra.B(BlockableEventLoop.java:175)
at bra.bA(BlockableEventLoop.java:152)
at flk.c(SourceFile:1296)
at flk.f(SourceFile:922)
at net.minecraft.client.main.Main.main(SourceFile:267)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:159)
at net.minecraft.launchwrapper.Launch.main(Launch.java:30)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Thread: Render thread
Stacktrace:
at fcg.b(SourceFile:308)

-- Incoming Packet --
Details:
Type: clientbound/minecraft:set_player_team
Is Terminal: false
Is Skippable: false
Stacktrace:
at yz.a(PacketUtils.java:112)
at gfx.a(SourceFile:131)
at gfx.a(SourceFile:110)
at yz.lambda$checkThreadAndEnqueue$0(PacketUtils.java:53)
at net.optifine.util.PacketRunnable.run(PacketRunnable.java:28)
at bra.d(BlockableEventLoop.java:210)
at bre.d(SourceFile:23)
at bra.B(BlockableEventLoop.java:175)
at bra.bA(BlockableEventLoop.java:152)
at flk.c(SourceFile:1296)
at flk.f(SourceFile:922)
at net.minecraft.client.main.Main.main(SourceFile:267)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:159)
at net.minecraft.launchwrapper.Launch.main(Launch.java:30)

-- Connection --
Details:
Protocol: play
Flow: CLIENTBOUND
Is Local: false
Server type: OTHER
Server brand: Paper (Velocity)

-- System Details --
Details:
Minecraft Version: 1.21.4
Minecraft Version ID: 1.21.4
Operating System: Windows 11 (amd64) version 10.0
Java Version: 21.0.3, Microsoft
Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Microsoft
Memory: 359608848 bytes (342 MiB) / 805306368 bytes (768 MiB) up to 2147483648 bytes (2048 MiB)
CPUs: 12
Processor Vendor: AuthenticAMD
Processor Name: AMD Ryzen 5 4500 6-Core Processor
Identifier: AuthenticAMD Family 23 Model 96 Stepping 1
Microarchitecture: unknown
Frequency (GHz): 3.59
Number of physical packages: 1
Number of physical CPUs: 6
Number of logical CPUs: 12
Graphics card #0 name: NVIDIA GeForce RTX 3050
Graphics card #0 vendor: NVIDIA
Graphics card #0 VRAM (MiB): 8192.00
Graphics card #0 deviceId: VideoController1
Graphics card #0 versionInfo: 32.0.15.6636
Memory slot #0 capacity (MiB): 8192.00
Memory slot #0 clockSpeed (GHz): 3.20
Memory slot #0 type: DDR4
Memory slot #1 capacity (MiB): 8192.00
Memory slot #1 clockSpeed (GHz): 3.20
Memory slot #1 type: DDR4
Memory slot #2 capacity (MiB): 8192.00
Memory slot #2 clockSpeed (GHz): 3.20
Memory slot #2 type: DDR4
Memory slot #3 capacity (MiB): 8192.00
Memory slot #3 clockSpeed (GHz): 3.20
Memory slot #3 type: DDR4
Virtual memory max (MiB): 34706.94
Virtual memory used (MiB): 14268.09
Swap memory total (MiB): 2048.00
Swap memory used (MiB): 0.00
Space in storage for jna.tmpdir (MiB): available: 74819.59, total: 475992.00
Space in storage for org.lwjgl.system.SharedLibraryExtractPath (MiB): available: 74819.59, total: 475992.00
Space in storage for io.netty.native.workdir (MiB): available: 74819.59, total: 475992.00
Space in storage for java.io.tmpdir (MiB): available: 74819.59, total: 475992.00
Space in storage for workdir (MiB): available: 74819.59, total: 475992.00
JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
OptiFine Version: OptiFine_1.21.4_HD_U_J3_pre11
OptiFine Build: 20250110-211831
Render Distance Chunks: 32
Mipmaps: 4
Anisotropic Filtering: 1
Antialiasing: 0
Multitexture: false
Shaders: null
OpenGlVersion: 3.2.0 NVIDIA 566.36
OpenGlRenderer: NVIDIA GeForce RTX 3050/PCIe/SSE2
OpenGlVendor: NVIDIA Corporation
CpuCount: 12

it also happens when i use the vanish command.

Shouldn't be related to PvPManager anymore, check /team list if there's no teams with name starting by PVP then it's clear.
Probably another plugin that uses teams and gets blocked by TAB too.