When I am creating a new card, the Front text block appears to be left justified. However when I save the card and view it in a study session, the text is centered. If I click on the Edit button on the bottom left to change the justification, the edit window shows the text is left justified.
The workaround I have found is to change the justification to center and then back to left. That seems to save it properly.
My specs: Ubuntu 24.04
Anki 24.06.3 (d678e393)
Python 3.9.18 Qt 6.6.2 PyQt 6.6.1
Platform: Linux-6.8.0-49-generic-x86_64-with-glibc2.40
In the note editor, left alignment is the default, so there is no HTML applied to make it that way. However your cards are built with the note type Styling and with formatting on the card templates as well. Center alignment is likely to be coming from those instead (and if you’re using a default note type, it definitely is). Styling & HTML - Anki Manual
(The reason setting alignment in your note to something else and then to left works is that Anki adds formatting to the field for that. You can see that in your underlying HTML by clicking < > above the field.)
If you want all text on all cards for notes of this type to be left aligned – controlling that from the note type Styling is the most efficient way. If you want it always for a particular card type or field, changing it on the Styling and/or card template is best.