Currently the possibility to adding text in Explore Dashboard Builder is unusable in Firefox (version 127.0)
- If a text is entered, it is partially not possible to select the text with the mouse (e.g. to change the format)
- After moving or resizing the text widged, the entered text is removed
The same works in Microsoft Edge and Google Chrom

Case is in status “Awaiting your Reply”, but I don't know, what you expect. In the meantime the new dashboard builder is in General availability and is still reproducible. This avoids configuration of dashboards using Firefox.
Please also check case #12686939. This issue could be reproduce by Dainne.