Time for journal reviewing / referring in mathematics - Is there a recent study? In the question: Lengths of review process of mathematical journals a nice question was asked and answered: how to compare journals in terms of time for the review processing. The article cited in the answer is quite nice http://www.ams.org/notices/201310/rnoti-p1390.pdf but is from 2013. Seven years after, are there some similar studies which can tell what kind of backlogs/ times needed for mathematical journals to accept / reject articles? A young mathematician asked me this today and I gave him the link, but a more recent one would certainly be more helpful.
The American Mathematical Society provides regular (annual, I believe) on journal backlog times. The latest can be found here: https://www.ams.org/journals/notices/201910/rnoti-p1713.pdf
Depending on your subfield it may not contain data on all relevant journals, but it is quite comprehensive. The reports are published in the November issue of the Notices of the AMS, which is also available online.

The data in the report is based on information provided by the journals itself.