you have been banned from /c/DataHoarder

You can do this with custom formats. You'd want to create a custom format that gives a score if the file is below a certain size threshold (say 1.5GB per hour), then add minimum custom scores to the release profiles you use (e.g. Bluray 1080p). You can also add custom filters for release groups that prioritise file size. YTS for example keeps their releases as small as possible.

You got a remux, which is uncompressed. You can turn those off in Radarr to avoid those surprises.

If you want to fine-tune your file sizes (and quality) further, you can set up custom formats and quality profiles. The Trash Guides explain it well, the "HD Blu-ray + Web" profile on that page is a solid starting point. It'll usually grab 6-12GB movies, but you can tweak it if you want them smaller.

It always throws me when I see at 1080 movie less than 5gb, then I scroll across and see it's x265....

Most modern devices should support x265 playback which has the compression sizes you are looking for.

In addition to setting the cap to file sizes for media, you can also blacklist tags like REMUX etc.

This is an example of a custom format for hevc/x265 files that are no larger than 6Gigs. You just need to create a new custom quality profile and give below custom format a positive/higher score.

{
  "name": "Minima",
  "includeCustomFormatWhenRenaming": false,
  "specifications": [
    {
      "name": "No mo than 6 Gigs",
      "implementation": "SizeSpecification",
      "negate": false,
      "required": true,
      "fields": {
        "min": 0,
        "max": 6
      }
    },
    {
      "name": "1080p",
      "implementation": "ResolutionSpecification",
      "negate": false,
      "required": true,
      "fields": {
        "value": 1080
      }
    },
    {
      "name": "eng",
      "implementation": "LanguageSpecification",
      "negate": false,
      "required": false,
      "fields": {
        "value": 1
      }
    },
    {
      "name": "Preferred x265",
      "implementation": "ReleaseTitleSpecification",
      "negate": false,
      "required": false,
      "fields": {
        "value": "[xh][ ._-]?265|\\\\bHEVC(\\\\b|\\\\d)"
      }
    }
  ]
}

Also check out Tdarr! I convert everything to HEVC using that. Shrinks down some files to literally 50% of their original size

You can edit the accepted sizes under Settings > Quality

In the profiles? Not sure if that's the correct term, but there's settings for all the quality profiles 720p 1080p etc with a slider that can set minimum and maximum size for that quality.

Use Quality Profiles and default to a lower quality. You can set the profile for each item when adding it, or change it after the fact.

https://trash-guides.info/Radarr/radarr-setup-quality-profiles/

https://trash-guides.info/Radarr/

Think the "Quality Definitions" section of the settings in Radarr is what you're looking for.

44gb for 1080 seems to be a remux file, which is the source of channel not converted but only repackaged. Just remove remux from your profiles and sed radarr to upgrade to other 1080 profiles by moving remux down in the list.