Testing Quick Look preview with files:
/Users/cfb/Downloads/a4k.net_1608911649.srt
2021-01-01 14:58:53.648 qlmanage[2167:87307] could not create directory "/Users/cfb/Library/Caches/com.apple.quicklook.qlmanage/WebKit/ServiceWorkers" for future sandbox extension, error Error Domain=NSCocoaErrorDomain Code=513 "You don’t have permission to save the file “ServiceWorkers” in the folder “WebKit”." UserInfo={NSFilePath=/Users/cfb/Library/Caches/com.apple.quicklook.qlmanage/WebKit/ServiceWorkers, NSUnderlyingError=0x7fc618fe5220 {Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"}}
2021-01-01 14:58:53.649 qlmanage[2167:87307] could not create directory "/Users/cfb/Library/WebKit/com.apple.quicklook.qlmanage/WebsiteData/LocalStorage" for future sandbox extension, error Error Domain=NSCocoaErrorDomain Code=513 "You don’t have permission to save the file “LocalStorage” in the folder “WebsiteData”." UserInfo={NSFilePath=/Users/cfb/Library/WebKit/com.apple.quicklook.qlmanage/WebsiteData/LocalStorage, NSUnderlyingError=0x7fc618e624d0 {Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"}}
2021-01-01 14:58:53.855 qlmanage[2167:87307] *** CFMessagePort: bootstrap_register(): failed 1100 (0x44c) 'Permission denied', port = 0xb203, name = 'com.apple.coredrag'
See /usr/include/servers/bootstrap_defs.h for the error codes.
2021-01-01 14:58:53.899 qlmanage[2167:87307] *** CFMessagePort: bootstrap_register(): failed 1100 (0x44c) 'Permission denied', port = 0x13e47, name = 'com.apple.tsm.portname'
See /usr/include/servers/bootstrap_defs.h for the error codes.
Not working on macOS 11.1 Big Sur, but force previewing works
Force previewing works
Output