There aren't exactly tonal issues in the sense that your writing comes across as unprofessional. However, the writing regardless does feel slightly amateurish. We were all there at some point and most of them are easy fixes.
kept within a 10m x 5m x 2.5m storage unit
For example is a tonal error many newer users fall into. Believing that the more precise they are the more scientific they are, containment cells and guard numbers and other laser-precise descriptions and procedures are put in place. However, keep in mind that it is actually more correct to simply state "kept in a storage container." Why? Because by using such precise measurements, you are telling the reader that if the cell was accidentally 9m x 5m x 2.5m then SCP-XXXX would break out, or explode, or be otherwise hard to contain. As most of these sorts of tonal issues are in your containment procedures, I would recommend keeping this guide on writing containment procedures open as a reference while you revise this part.
The other tonal issue that I saw popping up here and there is needless explaining. Consider these two examples:
Due to the objects cognitohazardous properties, the side of the case containing the up-facing side of the object is to be clearly marked
SCP-XXXX is to be indefinitely suspended as it is now confirmed that additional casualties may be produced in the death of the target of SCP-XXXX.
By explaining why everything/anything you write is necessary, you run the risk of doing two things(this runs true for most creative writing not just writing here). The first risk is that the reader is robbed of the sensation of figuring out that information on their own(this is guaranteed the risk is what follows) and reacts negatively. The second risk is that the reader gets the impression that you are either unsure of whether you convey the information properly, or unsure if the reader will understand your writing without the explanation. I recommend removing explanations like these because there isn't anything gained by keeping them in. A reader will not go "thank goodness this was explained earlier." Since doing this provides 2 possible detraction and no possible contributions, I recommend working around this in a more narrative fashion. Remove the explanation and make sure the information you want to convey is made crystal clear when needed. For the first example, you don't have to do anything because readers here assume every containment procedure is there for a specific reason. In the second one, you already pinpoint what incident led to the experimentation revision(this is fine) but the additional casualties aspect should be removed and self-explanatory when reading said incident. I understand that this is a bit meaty for such a small issue, but it is something that gets dinged quite frequently.
Regarding redacting, you do some of it awkwardly.
██/██/20██
Some readers have no problem with this. I'm part of the group that does. Consider the question: why censor dates? The logical response is because the censors don't want to have the date of an incident or event pinned down to corroborate with other incidents or events. However, by having the censors eradicate everything except the first 2 digits of the year(which is questionable in-universe), you give infiltrators a good 18 year time-frame to work with. It sounds like a lot but spies working with this time frame will get the job done a lot faster than spies working with hundreds of years with no references. I would recommend either redacting all of it, or none of it.
