Blocks placed on (certain) X or Z coordinates one less than a power of two are able to be clipped into/through by crouching/uncrouching (you can immediately sprint after uncrouching to make it through full blocks) when moving towards the origin.
My attempts to reproduce the bug in a singleplayer world have been much more inconsistent than testing on the realm I share with my friends, where we originally found this bug.
On the realm, Z=127 and 255 have worked, 255 being very consistent. 511 hasn't worked to my knowledge.
In the singleplayer world, X=255 as well as -255 have worked.
Testing in the singleplayer world has accidentally been done with swift sneak III, however in later testing I have been able to clip through doors and into blocks without it, although it is much harder to time.
Swift sneak has not been used in the testing on the realm.
Linked below is a video of the bug at Z=255 on the realm:
https://img.guildedcdn.com/ContentMediaGenericFiles/55c30dfff0bc849d3a8b1b7222076f5c-Full.mp4?w=1920&h=1080
Linked below is also a video of testing done in the singleplayer world at X=-255 (the iron bars were clipped through [with swift sneak III] after the recording was taken):
https://img.guildedcdn.com/ContentMediaGenericFiles/743e25e12e32c907408f34f63583cdfb-Full.mp4?w=1920&h=1080
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Despite MCPE-168969 being resolved as fixed in 1.20.60, this bug is still an issue in 1.20.62. The easiest and most consistent way (that I've found) of reproducing it is by using doors.

Relates to MCPE-39299.
They are the same cause, it's the floating point error changed your hitbox.
MCPE-39299 is already marked as "Won't Fix", so would this also "Won't Fix"?

Can confirm in 1.21.73.
Can confirm in 1.20.70.24 Preview, might be related to MCPE-178422.
Edit: updated version.