This behavior was introduced in 25w20a.
Bold text looks corrupted. I provided comparison images (the corrupted ones are from the latest snapshot, 25w20a). The unbroken ones were taken in 1.21.5.
MC-297812
Bold text is rendered differently than in previous versions
Resolved
Fixed
1
⬇️ Borked (25w20a): ⬇️
[media]⬇️ Intended (1.21.5): ⬇️
[media]