I tried the extension with a Magento 2 checkout flow (Luma based theme).
# in the cart
// Click on <input> #cart-51378-qty
cy.get('#cart-51378-qty').click()
// Click on <input> #cart-51378-qty
cy.get('#cart-51378-qty').click()
# in the checkout
// Click on <input> #ECIHNWG
cy.get('#ECIHNWG').click()
// Click on <input> #SERNC0C
cy.get('#SERNC0C').click()
This shows that using IDs is not always a good idea.
In the cart-qty input, there is the cart-id which would change on each run and thus is useless.
On the checkout page where I fill the name, address and so on, the inputs are generated by knockout JS and have always random IDs. There it would be better to use the input name selectors.
I know that especially the second case is hard to detect.
If the string "looks" very random, it might be autogenerated and not a meaningful.