I've also been thinking of making a feature request for an option to mark specific playlists to behave the "old" way, mainly for "bookmarks" and "watch later" type use cases. (Grid view, newest first, and don't open the whole local playlist, just the video (in its YouTube playlist if you were in one when you added it - the ones that have the playlist in their URL when you Share > Copy Link basically.)) I just hadn't gotten around to creating an issue to request it.

My duplicate issue:

The new playlists view is displayed as a list and less is visible on screen at any one time than before (pre v0.20). In v0.20 (with my current window size), I can see 4 video thumbnails in full on my screen in the Favorites playlist, compared to in v0.19 I could see 12 at once since a grid-based view was used.

Proposed Solution:

Allow switching between displaying playlists in list or grid view (and remember the state, not per-playlist, but globally).

Alternatives Considered:

A grid view makes less sense when wanting to order the playlist items, but for browsing it is arguably better. With the view mode being toggleable, we could switch back to viewing the playlist as a list to order them. In both view modes, we should still be able to order videos via the arrow buttons.

Retrieved from PikachuEXE#68 (comment)

I do like to add that normal playlists are also not viewable in a grid though.

Retrieved from PikachuEXE#68 (comment)

I think that's fair, but it's also worth noting that I think it's fine if user playlists have different styling choices and capabilities than remote playlists.

I usually prefer the list format but, in this case, I think the grid makes a lot more sense for "playlists" users do not intend to use as an auto-playing playlist. For example, I used my Favorites playlist just to save videos I'm interested in. I often go through and pick the ones I'm interested in from far back in the history and I have no interest in playing the videos in any order. Also, with the current layout, a lot of space is wasted on the left side.

As a side note, I don't particularly like the little icons floating on the video thumbnails. It's not too irritating but perhaps those could be floated below the channel name for each video or only displayed over the thumbnail on cursor hover. Currently, the "three dots" menu button only appears on hover and it is placed right of the video title. There is plenty of space below that menu button, so perhaps the new buttons could be stacked there, vertically. In a grid layout, the sorting arrows would probably not even be useful. Drag and drop might make sense there but probably isn't worth the trouble.

I was about to make this suggestion, I tend to procrastinate and the new lists are horrible for this use case (but great for the rest!). Having to select the list is also undesirable, especially when they change order.

Perhaps it would be convenient to automatically add the list of quick bookmarks to the sidebar, and when accessing from there display it in a grid.

I too use it as watch later and have the same issues.
A toggle for grid/non-grid and recent first/oldest first would solve this issue