this article gives a good account of the parameters determining the chemical stability of DNA. However it is incomplete and may give some false ideas.

First, contrarily to what is said, freeze-thaw  does break DNA chain, but only the very long molecules (1). This may explain the contradictions

Second, for room temperature storage in the dry state, in the absence of water, the situation is more complicated that it seems, because depurination and subsequent chain break still takes place (2).

Third, what is said about the   procedures for long term DNA preservation is largely incomplete.
Among other procedures there are matrices such as Biomatrica's (3) or Gentegra's (4). But as for FTA, the lack of protection from the atmosphere limits DNA's life time. Better is Grass' silica nanoparticles which completely mask DNA from air but still maintain some water (5). The best way has been shown to be DNAshells from Imagene company where DNA is kept under a neutral atmosphere maintained in a sealed stainless steel minicapsule. In these conditions, the DNA can be kept for thousands of years (2,6)

1 - Shao, W., S. Khin, et al. (2012). "Characterization of Effect of Repeated Freeze and Thaw Cycles on Stability of Genomic DNA Using Pulsed Field Gel Electrophoresis." Biopreserv Biobank 10( 1): 4-11.
2- Bonnet, J., M. Colotte, et al. (2010). "Chain and conformation stability of solid-state DNA: implications for room temperature storage." Nucleic Acids Res 38(5): 1531-46.
3 - Howlett, S. E., H. S. Castillo, et al. (2014). "Evaluation of DNAstable for DNA storage at ambient temperature." Forensic Science International: Genetics 8(1): 170-178.
4 - Kansagara, A. G., H. E. McMahon, et al. (2008). "Dry-state, room-temperature storage of DNA and RNA." Nat Meth 5(9): iv-v.
5 - Grass, R. N., R. Heckel, et al. (2015). "Robust Chemical Preservation of Digital Information on DNA in Silica with Error-Correcting Codes." Angew Chem Int Ed Engl 54(8): 2552-2555.
6 - Washetine, K., M. Kara-Borni, et al. (2018). "Ensuring the Safety and Security of Frozen Lung Cancer Tissue Collections through the Encapsulation of Dried DNA." Cancers .

Jacques Bonnet , Emeritus professor, university of Bordeaux, scientific director of Imagene company.