My Apple devices auto-correct the letter "B" to the numeral "4" when I try to use the letter as a single character.

I have to copy-paste the letter "B" if I want to write "Plan B" or when making alphabetical lists. It's infuriating. This happens on both my iPhone 15 pro, 2023 MacBook Pro 16" and it happened on previous devices also. All products were purchased new in France, my laptop has AZERTY keyboard and I frequently switch between both languages. What insanely simple solution have I not thought of?!