You can downgrade and this Dell support page has more information on the process. Your version allows downgrades up to version 1.3.3 which is an extremely old BIOS version.
  Hello, My Latitude 7490 worked well until a couple of weeks ago when I downloaded and installed a Bios update.  Now my boot up has slowed down and I get TWO Dell icon splash screens, one after the other, each one lasting about  ~5 seconds. The second splash screen has the small revolving icon underneath but not the first one. My present Bios is 1.32.0 dated 10/04/23 (installed a couple of weeks ago). I have been to the Dell website and downloaded Bios 1.31.1 which is shown as the version previous to what I have installed and this is saved in my downloads folder. Can I double click the 1.31.1 exe and install this over my present Bios?  I’m asking as I have heard various negative comments about reverting to a previous Bios.  I notice also that Microsoft has downloaded but not installed some 'optional updates' to my computer - which include  firmware 1.32.0.  This presumably being the same as what I already have installed...   Incidentally about the same time as I updated the Bios I cloned the C drive - a Samsung SSD 970 Evo Plus to a similar drive via an eternal enclosure connected to an USB port, disconnecting the  external drive after confirming that the clone was successfull.  I did read somewhere that this could confuse the Bios (?) so I have since checked using F12 and it shows just one option - UEFI Boot: Windows Boot Manager. Can I revert to a previous Bios ?  Is this safe? Thank you, John
Latitude 7490 Bios downgrade...