Replay Mod Version

replaymod-1.16.3-2.4.5

Fabric API Version:

Fabric-api-0.25.0

Problem description

With the exactly same Minecraft instance with Replay Mod I mentioned above, I tried to log in my server.
When I did not change my server platform from Fabric to Spigot, I could use Replay Mod and see its buttons.
However, since I changed my server platform to Spigot, I have not seen its "record" button again every time I log in the server with the same Minecraft instance.

I cannot find the cause of this problem on my own, and I need some help.
It will be highly appreciated if you could help.
Thanks in advance!

If you have no other mods installed (RM does not need the full Fabric API, it already bundles the parts which it needs), then I see no plausible way for the server software to influence those buttons.
If they're there in singleplayer but not in multiplayer, then the reason which seems most plausible to me would be that you accidentally disabled recording for servers (either in the ReplayMod settings or via the checkbox in the multiplayer menu).