Alert - Alert fires even though indicators show that it's below threshold

### Environment

SaaS ([https://sentry.io/]())

### Steps to Reproduce

[Customer link provided in internal case]()
But it's a metric alert on P90 span duration for Production data with a specific query
Thresholds are static and action step is to slack.

### Expected Result

Alert should have triggered on higher p90 duration according to the setup of the alert

### Actual Result

both Explore and the Alert dashboard it was triggering on show a lower number so we can't validate if that threshold has been hit which feels like a bug

This happend to both alert 74 as 76

It did mention the alert was modified but I can't check what has been modified and the customer told that they only changed the action step.

### Product Area

Alerts

### Link

[https://www.notion.so/sentry/2738b10e4b5d80c8bce0e865d4d7d464]()

### DSN

*No response*

### Version

*No response*

Start with the Alerts product area and review the linked customer case, then compare the metric alert configuration with the values shown in Explore and the Alert dashboard. Confirm the behavior for alerts 74 and 76 and document which threshold and P90 duration value were evaluated; done means the alert's trigger agrees with the displayed metric or the discrepancy is reproducible with a clear cause.

Written by the indexing model from the issue text.