STL repair tools outside of the computer graphics software tools such as Blender

perhaps i am just lazy or just dont want to put out the effort to learn Blender, FreeCad and the like …
i read somewhere, seemingly authoritative, that the process those programs use to export STL files had common flaws that the actual slice process didnt detect nor correct;

my tools are :
Prusa Slicer 2.6.1
Prusa Slicer 2.7.1
Ultimaker Cura 5.6.0
AutoDesk Meshmixer 3.5.474

why both versions of Prusa you ask ?
2.6.1 has a “fix with Netfabb” option; 2.7.1 replaced that with ‘fix by repair windows algorithm’ ( note that replacement is in the exact same place in the menu options as the netfabb previous option );
what i found was that if i send a newly gained STL to Prusa First i get the best results at the end of the ‘repair chain’;
Prusa has some error-checking at Import time ( as well as reporting what it found and what was yet to do; that is missing in the other tools );
then prusa has the menu ( right click) options mentioned above;
i read somewhere that Fixfabb is quite an operation, highly respected German company;
until recently i think they had a free online service ( maybe that is what prusa was actually using);
after the 2 steps regarding prusa, i export then and send to meshmixer (“MM”) to use it’s Inspector tool (under Analyze menu);
i tried reversing meshmixer and prusa and i found that on occasion MM would just tear up a model on it’s attempt to Inspect and fix it; so i inserted prusa as the initial step;
i have on occasion seen MM catch and fix errors that prusa didnt;
after all that i export and send to cura, cura has an initial import check for water-tightness as well as mesh tools;
after an export there, i send to Bambu Studio; it seems Bambu error checking is only done at slice step;
just today i went thru my normal, Prusa, MM ( okk i did skip the cura step today…);
then slicing in Bambu showed an empty layer error !!
how could that have gotten by the prior error-checking ?
inspecting the model closely in MM ( which i think has the best visual checking) i could see the open layer; ( i suppose a cura slice could have shown that empty layer);
does anyone have their own system which they trust ?