Summary:
In 24w13a when armor stands with the weaving effect were destroyed, they could place cobwebs around them similar to mobs. In 24w14a this stopped working. As of 1.20.5 Pre-Release 1 it reduces the speed reduction in cobwebs for the armor stand, meaning it only partially works on armor stands. It is worth noting that effects like slow falling, dolphin's grace, levitation, oozing, wind charged and glowing work on armor stands as expected.

Steps to reproduce:

1. Build a pillar of cobwebs
2. Place an armor stand in the cobwebs

3. /effect give @e[type=minecraft:armor_stand,limit=1,sort=nearest] minecraft:weaving infinite 0

4. Place another armor stand outside of the cobwebs
5. Apply the weaving effect to that armor stand too using the following command:

   /effect give @e[type=minecraft:armor_stand,limit=1,sort=nearest] minecraft:weaving infinite 0

6. Break the armor stand

Observed results:
The weaving effect causes the armor stand to fall through the cobwebs faster but does not cause it to place cobwebs when destroyed unlike in 24w13a.

Expected results:
The weaving effect should cause the armor stand to place cobwebs upon being destroyed too just like in 24w13a.

Note: This is closely related to MC-66645 but I wouldn't consider it a duplicate of this. The comment only states that armor stands are not affected by potions, which is intended per the fix of MC-91050. As mentioned above, some effects work on armor stands when applied using commands.