swing feature

Give us an example file with the problem.

So there's most probably sone staff or system text with swing set on in it's properties.
See also https://musescore.org/en/handbook/3/swing

If you really cannot track down the problem, try this:
1. Use File > Save As... to save your score as *.mscx format (Uncompressed MuseScore 3 File).
2. Open the *.mscx file in a plain text editor (on Windows: Notepad or Notepad++).
3. Search for text which denotes a Swing instruction: <swing unit=.../> - see XML example below.
4. Note the actual contents of the <text>...</text> element - which is "Swing" in the XML below.
5. Re-open the *.mscz file in MuseScore, and search for that text in your score. Delete the offending text.

      <Measure>
        <LayoutBreak>
          <subtype>line</subtype>
          </LayoutBreak>
        <voice>
          <SystemText>
            <swing unit="eighth" ratio= "60"/>
            <style>Tempo</style>
            <text>Swing</text>
            </SystemText>