Engineer combat res is a joke

[Grendiser-kazzak (Grendiser)]

According to hotfix notes, blizzard said that the maximum success chance should be equal to the shadowlands variant.

Here is the link to the post
(WoW Hotfixes - Updated 20 March)

And here is the quote from the blue post

• Tinker: Arclight Vital Correctors now has a slight bonus to success chance for Engineers, with its maximum success chance equal to the Shadowlands variant.
  • Developers’ note: There are multiple avenues of progression to increase your gadget success chance in Dragonflight, and the difference between a newbie Engineer and an experienced tinker is substantial. However, it is clear that the gameplay did not support the fantasy and instead resulted in mostly frustrating experiences. These adjustments are intended to address many of those pain-points while maintaining the feeling of progressive mastery. While we will not be sharing exact values, we would also like to clarify that an Engineer with all 4 Safety specialization nodes and a Quality 3 tinker will reach the maximum success chance and do not need to use the Calibrated Safety Switch optional reagent. We will look for opportunities to make this system more transparent in future patches. Thank you all for your feedback!

So may be there is a bug that makes the chance less than what they said? May be you were extremely unlucky?