For Gallery not accessible from certain apps issue, go to Settings > Apps > WhatsApp > Permissions and give permission to Photos and Videos. Do the same for other impacted apps.
@elisha87 Certainly check the permissions as @Neo001 suggests. However with other issues and things like creashing,lagging some advice here. Do you have the latest updates from the Samsung and Google stores? Have you wiped the cache partition which is generally advisable after updates, temporary files are deleted but no data is lost.
1. Turn off the device.
2. Connect To Computer or plug in USB-C Headphones , Press and hold the Volume Up key and then press and hold the Power key
3. When the Android logo displays, release all three keys.
4. An 'Installing system update' message will show for 30 - 60 seconds before the Android system recovery menu options appear.
5. Press the Volume down key several times to highlight wipe cache partition.
6. Press Power key to select.
7. Press the Volume down key to highlight yes, them and press the Power key to select.
8. When the wipe cache partition is complete, Reboot system now is highlighted.
9. Press the Power key to restart the device.
you can also Repair Apps from the same Recover Menu.
Some known Bugs and ppossble fixes in this article,scroll down to One UI 5.0 Bugs
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 5.0,Android 13 .