I can corroborate that upgrade to 2024R1.4.1 has totally hosed my dashboards.

Thank God I tried it out on DEV first. PITA to have to rebuild my DEV box and restore from backup, but better than having my PROD box hosed.
In my home dashboard only Host Status Summary and Service Status summary are somewhat readable, tho they did reduce in size. All other dashlets are shrunk down to 1/2 postage stamp size. So small cannot access dashlet controls to bring them back up to size.
Another dashboard, when I open it, red message at top " Error: Access denied due to cross-origin policy or content security policy." I'm an admin, of course so what gives?. And all of that dashboard's dashlets are scaled to huge and moved around. Or are they just so huge that they just
look like they moved? IDK.
Yeah, not upgrading PROD 'til this is fixed. Apologies to Forrest Gump. Nagios is like a box of chocolates . . .