To reproduce run "vidcontrol -f gallant" when using the vt_vga driver. Resulting output appears as in the attached screenshot. vt_efifb or i915 framebuffer is fine. Gallant is 12 px wide. It looks like character positions that don't start at an 8-bit boundary (i.e., every other column) get shifted left to the previous 8-bit boundary, overwriting part of the previous column's character.
Created attachment 144382 [details] QEMU screenshot of vt_vga with gallant font loaded
Notify possibly interested party.
Original fix for this issue (r269471) introduced a significant performance regression. New interface introduced in r270322 restores adequate console speed.