At first I thought my issues were related to Windows, but I'm experiencing the same behavior in Linux as well (and also using slash to transform any Windows-specific paths).

I've created a test repo here: https://github.com/dlong500/node-cli-base

In my real projects I'm using several types of glob patterns, but the test repo above demonstrates a relatively simple pattern:
/opt/nodejs/node-cli-base/testdata/test?/?

Assuming a testdata folder contents of the following folders:

/opt/nodejs/node-cli-base/testdata/keep/
/opt/nodejs/node-cli-base/testdata/keep/textfile.txt
/opt/nodejs/node-cli-base/testdata/test1/0
/opt/nodejs/node-cli-base/testdata/test1/1
/opt/nodejs/node-cli-base/testdata/test1/2
/opt/nodejs/node-cli-base/testdata/test1/10
/opt/nodejs/node-cli-base/testdata/test1/11
/opt/nodejs/node-cli-base/testdata/test1/12
/opt/nodejs/node-cli-base/testdata/test2/0
/opt/nodejs/node-cli-base/testdata/test2/1
/opt/nodejs/node-cli-base/testdata/test2/2
/opt/nodejs/node-cli-base/testdata/test2/10
/opt/nodejs/node-cli-base/testdata/test2/11
/opt/nodejs/node-cli-base/testdata/test2/12

I would expect the following folders to be deleted:

/opt/nodejs/node-cli-base/testdata/test1/0
/opt/nodejs/node-cli-base/testdata/test1/1
/opt/nodejs/node-cli-base/testdata/test1/2
/opt/nodejs/node-cli-base/testdata/test2/0
/opt/nodejs/node-cli-base/testdata/test2/1
/opt/nodejs/node-cli-base/testdata/test2/2

I get the expected result with del v4.1.1, but no folders are deleted at all with del 5.1.0.

What exactly am I doing wrong? I've read through all the documentation and it doesn't seem like any glob pattern syntax has changed. I've also tried passing extglob: true, onlyFiles: false, and caseSensitiveMatch: false just to see if the behavior changes (even though I believe those are defaults) to no avail.