In addition to having the same issue as another user (wherein the targeted mob does not move with the HUD display, but rather stays in the top left), I have an issue where random blocks/entities in the world turn a bright green (or whatever color, I assume, is the color used for "health indicator/HP added".
So far, I have seen bells turn a bright green when looked at (it's not really an exact science of when it triggers, but you can move your cursor over the block and it consistently will turn bright green). I have also observed this with beds, leads (on a fence), and player heads in multiplayer (but rest assured this issue also occurs in singleplayer worlds, too).
I know this issue is not limited to my resource pack as it happened with the default pack (first image) as well as the second (FaithfulVenom 32x pack).

Bummer, I was hoping it was fixed in the later versions. If you can narrow it down to 3 mods or less then yes, that would be helpful.

This problem only occurs when fast render is on
@frodare
mods:
fabric-api-0.37.1+1.17.jar
list.txt
modmenu-2.0.4.jar
optifabric-1.11.18.jar
preview_OptiFine_1.17.1_HD_U_G9_pre32.jar
torohealth-1.17.1-fabric-10.jar

This sounds similar to when we would modify the GL stuff then not set it back. Can you get the current RenderSystem state before you modify it here: https://github.com/ToroCraft/ToroHealth/blob/master/src/main/java/net/torocraft/torohealth/bars/HealthBarRenderer.java#L164

Then reset it to that before you leave that method? Don't know why that would only sometimes change the color like that, but maybe certain renderers don't set the state of the RenderSystem properly before using it.

I never was able to reproduce this issue, but I did hear of it from multiple people. Was this fixed in the latest versions?

Well, I've found that it goes away with the F3 menu pulled up, but outside of that it still happens pretty regularly. If it helps, I can list the mods I'm using in conjunction with this one as well as my specs.

Bummer, I was hoping it was fixed in the later versions. If you can narrow it down to 3 mods or less then yes, that would be helpful.

This might be fixed torohealth-1.17.1-fabric-11.jar. I was never able to reproduce this issue, so I will leave it open for awhile for anyone to report back if the issue is still occurring.

Seems like whatever you did fixed it.

Running the following:

• fabric-api-0.37.2+1.17.jar
• litematica-fabric-1.17.1-0.0.0-dev.20210713.103711.jar
• malilib-fabric-1.17.1-0.10.0-dev.24.jar
• modmenu-2.0.4.jar
• optifabric-1.11.18.jar
• plasmovoice-fabric-1.0.11.jar
• preview_OptiFine_1.17.1_HD_U_G9_pre32.jar
• torohealth-1.17.1-fabric-11.jar

Thanks for reporting this. I will update to the latest fabric version and work on a fix for the next release.

File torohealth-1.17-fabric-6.jar fixes the issue with entity location. I haven't been able to reproduce the color issue yet.