I'm using Indesign 20.5 on an Intel Mac Pro running Mac OS Sequoia 15.6.
Here are the steps to reproduce the issue:
1. Insert a new text box and enter some English text.
2. Select the text
3. Change the keyboard input to Hebrew.
4. Start typing in Hebrew.

The resulting text will be an English letter (corresponding to the Hebrew letter typed in) followed by the correct Hebrew letters typed.
Two things to note:
1. You must select all the text in the text box for this issue to take place.
2. For some reason Adobe fonts are immune to this issue