youtube regression: output template "abr" is "NA"

[bughit]

Checklist

• I'm reporting a broken site support
• I've verified that I'm running youtube-dl version 2021.02.04.1
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar issues including closed ones

Verbose log

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-f', 'bestaudio[ext=m4a]', '-o', '%(abr)sk.%(ext)s', '-v', 'tYO8a0I6lX8']
[debug] Encodings: locale cp1252, fs utf-8, out utf-8, pref cp1252
[debug] youtube-dl version 2021.02.04.1
[debug] Python version 3.9.1 (CPython) - Windows-10-10.0.19041-SP0
[debug] exe versions: ffmpeg 4.3.2-2021-02-02-full_build-www.gyan.dev, ffprobe 4.3.2-2021-02-02-full_build-www.gyan.dev
[debug] Proxy map: {}
[youtube] tYO8a0I6lX8: Downloading webpage
[debug] Invoking downloader on '...'
[download] Destination: NAk.m4a
[download] 100% of 950.87KiB in 00:00

Description

At some point %(abr)s for youtube became "NA". "-F" still shows audio bitrates, so "abr" should be available.

140          m4a        audio only tiny  129k , mp4a.40.2 (44100Hz), 950.87KiB

[bughit]

@dstftw The abr now has 3 decimal places (129.473). Should be truncated or rounded to a whole number.