i dont think it is stronger. As you have already noted - the platform growth has to be accounted for primarily at minimum.
Then for stronger reasoning, there are factors of geographic coverage (either year could have observations that are not comparable - that is say if 2024 has say 10k observations from observers in some remote region from various reasons like coordinated nature programs, observers trips, observers popping in that area from CNC which is factually major bump in inat data — while 2025 did not), observer effort (are some observers duplicating more and how much did they duplicate observations in 2024 vs 2025), uniqueness (did 2025 have more uploads of temporal than 2024 for single species in reality - aka if users uploaded lifestages or observations of same organism everyday or if set of users saw same organism across days in one year over another; so in reality such observations will not be truly answering question of - are X taxa decreasing), diversity (it could just as well be case that only some set of Species observations may have increased from multiple factors like - accessibility and invasiveness of that species, how cool it looked to catch eye of photographer and get uploaded by multiple observers, regional factor and observers bias within that region, …), user activity (observers passive in one year, active in another)
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so a strong signal question would be “Given stable sampled cohort of quality iNaturalist observers, who has similar or comparable spatial activity in both year 2024 and 2025, and then callibrated with their per-unit-encounter-activity-and-spatialheterogenity-and-effort, did a statistical model (say heirarchial bayesian model or negative binomial mixed model) signal indicate decrease of taxa or increase”
There is also another factor of climate change and any programs ideology shifts in 2024 and 2025 which maynot be apparent in direct end data.
For example, say CNC 2026 wants to shift to quality over quantity which will see major numbers trend change in next year iff goals works reasonably, National moth week india wants to shift dates for India specifically that fits with regional moth richness months - if so the increase in species observations will be majorly from such change rather than increase in taxa, climate change shifts species months and regions and altitude of species from lack of habitat or temperature shifts - and this signal isnt decoupled easily too from just count of observations signal.