Snapshot 24w34a: We Have Been Heard!
Thanks to @enbyd for helping me set the world up! Apologies for not replicating the bug properly...
Mended Minecarts is the name of the mod, in case anyone was curious: https://github.com/2No2Name/MendedMin...
Links to the mentioned bug reports:
https://bugs.mojang.com/browse/MC-275791
https://bugs.mojang.com/browse/MC-275...
https://bugs.mojang.com/browse/MC-275758