Hi,
Sorry to everyone who had followed-up and/or asked if I found a way to solve this... I just abandon this post because... Well, nobody cared for month. There is activity and reactivity for common questions, not for issues.
I never found the culprit, either being Forge itself or a specific mod, and never find a way to trigger the bug without the "intermittency part"
@deus_ ChatGPT did what it does best, putting words one after another, and led you to trying to fix "code" with obfuscated java methods... While we are doing modpacks here ^^'
I did try removing mods one by one, and stumble with the "7 times in a row, I think this time I get rid of the little bugger! Oh... It happen again..." too.
Anyway since nobody know what can cause that bug, and the intermittency, we can't assume that removing a mod will solve the issue because any later version of another modcould trigger this bug aswell. I highly suspect that Forge is the real problem here, not a mod.
@Sniper_Gecko I have, in fact, an idea to address that: changing platform for future modpacks. The split occur for a reason, and severals mods only support the fork now.
Good luck everybody and I hope someone could help you