This version, beta 184.108.40.206, is the fourth development version for 1.16.210. The "210" in the third segment of this version means that this is the first minor supplementary release after the second major supplementary release of 1.16. If the third digit was incremented, that would represent a bug-fix supplementary release.
So, 1.16.210 is to be a minor supplementary update to 1.16, and this is represented in the features added in this new beta, of which there are only three.
The three new features in this beta are as follows: a new text-to-speech option has been added to the audio settings menu to control the volume of speech output; the
/camerashake command now has the ability to stop the current shaking action; and the
/structure command now has the ability to delete saved structure lists.
Nothing major among that changelog, however, of course, the features are never the only part of this beta.
Notable changes due to bugs being fixed in 220.127.116.11 are that ink sacs obtained from wandering traders can now be used in crafting, screen reader support for the emote wheel on mobile, and the saving of split-screen players' characters when they rejoin the world.
This release is still a supplementary one for finalising the 1.16 Nether Update, hence the version number, but development of the new Cave & Cliffs update should be starting relatively soon for Bedrock edition – be on the lookout for the 1.17 betas.