Same version of Joplin, different CSS elements?

Operating system

macOS

Joplin version

3.5.13

Desktop version info

Joplin 3.5.13 (prod, darwin)

Device: darwin, Apple M2
Client ID: da11febc41b34c46bbafb860a0008da8
Sync Version: 3
Profile Version: 49
Keychain Supported: Yes
Alternative instance ID: -

Revision: 0c1511f

Backup: 1.5.1
Joplin Batch: 0.2.2
Note list and sidebar toggle buttons: 1.0.3
Quick Links: 1.3.2

Editor

Markdown Editor

What issue do you have?

I have the identical versions of Joplin installed on my M1 Macbook Air and M2 Mac Mini. (identical plug-ins and settings as well) They use the same userchrome.css files, but the element names on the M1 are different than the M2 when I use developer tools and select the same element in the same note...

On the M2, selecting a header 2 element returns:
div.CodeMirror span.cm-header-2

but on the M1, selecting the same header 2 element returns:
.ͼ4e .cm-h2

What would cause these to be different?

thanks!