If you notice that
<g> tags are being inserted into your WYSIWYG's source code, for example:
<g class="gr_ gr_00 gr_alert gr_gramm gr_spell" data_gr_id="00" id="00">Here is some content.</g>
The likely culprit is the Grammarly browser extension. You can remove those tags from the WYSIWYG and disable the Grammarly extension in your browser to ensure they're not re-inserted.