This is the real impactful change. This is for ALL STORAGE CLASSES, not just Coldline. As someone who manages billions of objects in GCP, I know very well that each of those object write is a Class A operation, so 2x in price.
Also keep in mind that anyone storing objects durably (DR, anyone?), e.g. your customer data, is using multi-region, so this is a notable cost impact.
Note that there is a curious inflection point where, the Class A/B operations on an object cost _more_ than the (bytes) storage cost, depending how long you retain the data. That's where this is very impactful.
Annual multi-regional Standard _storage_ cost for a 19MiB object
e.g. 0.026 $/(GiBmo) 12 mo/yr * 19 MiB/yr = 5.95E-06 $/yr/obj
Annual multi-regional Standard storage cost for an object that you 1x write (A), and 2x read (B).
e.g. 0.05/1e4 $/A req + 2 * 0.004/1e4 $/ B req = 5.80E-06 $/yr/object
Here we see that the old annual "storage" carrying cost for this 19MiB object was less than the "request" cost. Now double the cost of the operations and you should consider storing fewer, bigger objects.