Game doesn't load a 3x3 area around the destination portal for 15 seconds whenever there isn't a portal within range forcing the game game to generate a new portal. Area does stay loaded in 1.16.1 but not in 1.16.2 or 1.20.2

What I expected to happen was...:
Area should be loaded for 15 seconds as it does when there is already a portal within range in the destination dimension. 

What actually happened was...:
Area doesn't stay loaded for 15 seconds and unloads whenever the player leaves.

Steps to Reproduce:
1. Create new creative world
2. Make and light a nether portal
3. Place and activate a repeating command block with the command "say overworld"
4. Copy location with F3+C
5. Use the portal to get to the nether
6. Break the portal in the nether
7. Place and activate a repeating command block with the command "say nether"
8. Paste the location copied earlier into chat and use it to return to the overworld portal
9. Go to the nether and immediately back to the overworld using the nether portals
10. Observe that the repeating command block in the nether stops writing in chat when u leave the nether instead of 15 seconds after entering the nether