It's not necessarily "bad" that those outlets are all on the same circuit and protected by the GFCI in the upstairs bathroom, but it's certainly not ideal and likely not originally intended by the electrician. Here's why

Why it's not ideal/problematic:
Inconvenience

As you've already discovered, a single trip in one bathroom knocks out seemingly unrelated things. This can be a major annoyance. You want a GFCI trip to be localized to the area where the problem likely occurred.

Over-Protection

GFCI protection is most critical in areas with a high risk of water exposure (bathrooms, kitchens, outdoors, garages). While extra protection isn't inherently bad, having everything daisy-chained off one GFCI can lead to unnecessary tripping and the inconvenience mentioned above.

Potential Misinterpretation

Someone using the outdoor outlet or garage outlet might not immediately associate the problem with a bathroom GFCI. This can lead to frustration and wasted time troubleshooting.

Troubleshooting Nightmares

Finding the actual source of a problem when multiple outlets are on the same GFCI is more difficult. The trip could be coming from ANY of those protected outlets, not just the bathroom.

Overload

While less likely with a GFCI tripping, having a lot of outlets on one circuit increases the potential for overloading that circuit, especially if multiple high-draw devices are used simultaneously. However, the GFCI is tripping before this can likely happen.

Why it might have been done this way



Cost Savings

Wiring multiple outlets off a single GFCI is cheaper because it requires less wiring and fewer GFCI receptacles. GFCI receptacles are more expensive than standard ones.

Code Compliance at the Time of Installation

Older electrical codes might not have been as strict about GFCI placement. What was acceptable 20 years ago might not be today.

Do you need to resolve it?YES, you should strongly consider resolving it. While it might not be an immediate safety hazard, the inconvenience and potential troubleshooting issues warrant a fix.

Here's what you should do


Call a Qualified Electrician

Electrical work can be dangerous if not done properly. Don't attempt this yourself unless you're very experienced in electrical work and understand the code.2.

Explain the Situation

Tell the electrician exactly what you've observed (outlets affected, the triggering GFCI, etc.).3.

Discuss Options

The electrician will likely recommend one or more of these solutions:

Separate GFCI Receptacles

Install dedicated GFCI receptacles in each area where GFCI protection is needed (garage, outdoor outlet, downstairs bathroom). This is the most robust and desirable solution.

GFCI Breaker

Replace the existing circuit breaker with a GFCI breaker. This protects the entire circuit with GFCI protection. However, it doesn't solve the problem of one trip affecting multiple areas, so individual GFCI outlets are likely more ideal.

Rewiring (Less Likely)

In rare cases, the electrician might recommend rewiring some of the outlets onto different circuits. This is the most expensive option but might be necessary if the existing wiring is inadequate.

In summary, while technically functional, your current GFCI setup is not ideal and can cause a lot of frustration. Hiring a qualified electrician to install separate GFCI protection for each area is the best way to address the problem and ensure proper electrical safety and convenience. Flag for review